Synthetic motor oil

ruking1 · January 2005

In a word, yes.

I almost never stay awake till 2 am to post about oil!

Bobstheoilguy has many VOA's and more importantly UOA's posted. So if you want stimulating real world experiences, a good read to bone (bore) up on the subject!!

Actually Shiftright, from a devils advocate point of view, does right to present the other side. I have used synthetic (specifically Mobil One products) for so long that really A/B testing is not on my mind (694,000 miles) The reality is most of my later model cars came with synthetic oil. In those cases there really was no change of mpg, except for when I changed the conventional ATF to Mobil One ATF on my Corvette Z06. Just this one change garnered app .5-1 mpg better. So I am glad that the Honda Civic does have conventional oil so I will indeed see if I do get the 1-3 mpg better that research as indicated might be true.

yurakm · January 2005

Interesting.

I did not notice any improvement in fuel consumption with my 2000 Buick Regal GS after flushing old ATF by Mobil 1 at about 35k miles. However, it would be hard to notice the small improvement. I do not record how much fuel I am buying.

My wife and I notice, however, that with both our cars we have to brake often when following other cars in traffic. I mean, while we are moving on idle, on flat terrains or downhill. Often when following cars of the same model. It clearly shows that our cars have lesser friction.

The other car was a 98 Chevy Malibu, recently sold. Engine was filled by Mobil 1 motor oil for years, but transmission had factory ATF.

I believe, the reason for lesser friction with our cars is/was not a better oil, but better tires. Firestone Firehawk SH-30 with the Malibu, Bridgestone Potenza RE950 with Regal. In addition, we are/were inflating the tires a bit higher than recommended by GM.

yurakm · January 2005

Merely more sporty tires with more rigid sidewalls, and / or higher inflation, would guarantee a manufacturer [substantial] increase in fuel mileage. However, hardly any manufacturer is doing it, except with performance cars.

ruking1 · January 2005

It might sound like passion, but for me it is ... boring...

As some other posters have noted, the drive train components work in tandem and works to give you a fairly consistent parasitic drive train loss. As is fairly obvious there are wide ranges of variables and perceptions. So when one is trying to narrow down what is causing the changes, it helps to really isolate the variables.

When it comes to gassers fuel mileage, the oems have pretty much picked all the low hanging fruit. An example might be the new 5w20 standard down from 5w30, which is down from 10w40. So for example the conversion from conventional ATF to synthetic atf is on the order of between 1.5 % to 3%, really not much to speak of. But I think ultimately we are dealing with a host of goals, compromises, etc. For example if mph was really a big priority then why are the majority of passenger cars automatic transmissions that get way less mpg? You can contrast this with the European passenger fleet (it is monolithic in some senses) where the majority of the passenger cars run manual transmissions, which of course get better mpg.

andyman73 · January 2005

Ha ha ha....you made me laugh!

Actually, I am awake many nights at 2am, because I work nights. I am one of the few without a home pc. So I catch up on my forums here at work. I work from 1800hrs to 0600hrs.

So you don't have to be concerned about my being over passionate about oil.

But I do appreciate your concern for my well being.

Oh, and I do think it is that good.

marsha7 · January 2005

still too new to know if they last longer with synthetic (my 88 Prelude went 188K and my 88 Legend went 165K on dino oil, and removing valave covers on both of them revealed valve springs and heads that were as clean as they day they were new), but I have converted to syn oil thanks to these posts...

Do they make synthetic transmission fluid for Crown Vic and Ram 1500, or, for that matter, synthetic power steering fluid, synthetic rear end gear oil (regular and/or posi)...

andyman73 · January 2005

I believe Red Line makes a host of synthetics for all your automotive needs. And some other makes also. I believe that the tranny and differential oils are universal, or atleast, wide ranging.

Mr_Shiftright · January 2005

Yes but I don't think the two examples are comparable. You can get better fuel mileage any number of ways but most compromise ride or handling or noise, etc.

A 10% increase in fuel mileage from using synthetic oil would be an astounding, inexpensive, unobstrusive and simple alternative to the hundreds of millions of dollars automakers' spend for increases in fuel economy.

I don't believe that sucha figure would hold up to rigorous scientific testing for that very reason---the automakers know it won't give that type of a result.

Of course, there are many other benefits and other reasons for using synthetics that do bear up under scientific scrutiny.

beernut · February 2005

Is that GMT?

ruking1 · February 2005

Again, your take highlights the the myraid of multi-level compromises and the almost maddening plethora of choices inherent in getting any auto to market.

On the foreign car side, the Michelin MX?? Energy is almost a OEM staple at least on MB E20 and VW Jetta as an illustration. The tire is known as an fuel saving tire, i.e., 1-5 mpg over any number of replacement tires. Specificially, it is known to have "less rolling resistance". Oxymoronically, there are no real published standards for this "less or more rolling resistance") and in fact, no basis of comparison among and between tires. Yet this oem tire is hard riding (per se) and up to 2-4 x more expensive than other tires and does not last very many miles for its cost and lacks performance also, comparatively.

Mr_Shiftright · February 2005

Well that sounds like wonderful advertising anyway, if in fact there are no standards for what the term means.

At least with synthetics you can see testing standards.

ruking1 · February 2005

In regards to the synthetic the standards are stated and verifiable. But the nexus: what are the compromises? To me synthetic is another arrow in the quiver, so to speak. It allows me to do stuff, for example, that not too long ago was considered like falling off the face of the flat earth.

So as you probably would agree, synthetic is not all things to all people. Or, not the perfect application for everything.

andyman73 · February 2005

Well, it's Military time, based on a 24 hour clock. In laymans terms 6 pm to 6 am. And since I am in PA, same time zone as you. Hope that answers your time question, Jerry.

Beernut, nice handle.

beernut · February 2005

wtd44 · February 2005

Just buy hydrocracked Chevron/Havoline with "Isosyn" and you'll never turn back to overpriced synthetics. >:o]

Mr_Shiftright · February 2005

oh ruking, now you're going to have to tell us how synthetic oil made you into a super-hero

I want to be one, too!

Actually, it's great for racing--all my friends who race (seriously race I mean) use it.

I'm not putting it in the current older Porsche though---I am still leery of oil leaks, especially with an engine known for oil leaks to begin with, which doesn't have any at the moment.

When very experienced engine builders caution about leaks, I'm not saying I believe them outright, but it does make me hesitate. I'd love to try it, but...

ruking1 · February 2005

For me I REALLY like changing oil at 15,000 mile OCI rather than 3k-5k intervals!!! Now that to me is SUPER!:) Some of the other benefits are not so noticeable. I like NOT using 37.5 qts(3k intervals vs 7.5 qts(15,000k intervals) of oil. This will obviously add less to the recycle waste stream. Our municipality take away used oil as part of the WSG bill and of course if this is done at a shop they usually charge waste disposal fees. Some municipalities do not even take used oil so it might be a bit different in each locale. I also understand some auto shops take used fluids also.

There is an uglier side also. I have read in several places that folks without a "convenient" place to dispose oil do so directly to the environment! This of course "pollutes" the environment. i.e., finds it way to the water supply, etc. etc. The estimate is 2-4x the crude oil lost during the Exxon Valdez accident PER YEAR!!!!

armtdm · February 2005

Yes

It took me several years of synthetic use and used oil analysis reports to get to feeling really comfortable with it and using it for extended drains, up to about 12,000 miles per change depending on vehicle and usage.

Stuff works

Mr_Shiftright · February 2005

I would never go 15,000 miles on a change myself. I don't really see the point. My engine is worth $15,000, my car is worth $8,000.

ruking1 · February 2005

Like I said about falling off the flat side of the earth...!

wtd44 · February 2005

I started with mineral oil, evolved into synthetic lubricants, then elected to return to mineral oils. Join me and save your money. If you're a serious racer, please disregard this posting.

shipo · February 2005

Errr, what about those of us who have cars that specify synthetic only? How about those of us who like extended oil changes? How about those of us who like the fact that when the OAT is thirty below zero, our engines still turn over like it was the middle of summer?

I was an early adopter of synthetic oil (late 1970s), and I'm sticking with it, slippery though the topic may be.

Best Regards,

Shipo

wtd44 · February 2005

You make a good point! Now, if the syn oil makers would stop their avaricious pricing practices...

ruking1 · February 2005

To me there is NOTHING wrong with mineral oil. I have also run 250,000 miles on a vehicle using nothing but mineral oil (just before Mobil One came to market). The changing schedule was frenetic (1500/3000 miles). And these were the days before UOA's were available.

In days past, sometimes 3000 miles was PUSHING IT! The problem then was there was no economically viable option to verify it. So as a "policy" one changed it! So a lot of unsubstantialed hype grew up around 3000 mile OCI's. So it is not surprising whole industries grew up around this multi billion dollar potential! Qwiky Lube statistics, as reflected in industry rags, point to the average car owner doing 5,000 mile OCI's. The research, the write up points out shows the average owner has done an average 2000 mile drift to (oblivion) 5000 mile OCI's due mainly to lifestyle choices of the owners and not the vehicle requirements. This continental plate drift really punches holes in the qwiky lubes numbers. So goal is to "beat back the OCI's from 5000 to 3000 miles. Also not many folks know that buried in those SJ/SL/GF-2 standard drifts, is the fact the oil is designed to last longer between OCI's. But then again, to me; the major point about mineral oil: the major data point was (and for most folks STILL is) the mantra of 3000 miles.

Again to me major data points SHOULD be UOA's of conventional oil!!! So if I was a qwiky lube owner, why would I want a test to verify that ExxonMobil 5w20 oil is still good to go at 9100 miles when my whole business is built around 3000 mile oil changes????!!!

I had also been skeptical of 0w20 Mobil One and other oems' 5w20 viscosities. So there are data points both VOA and UOA demonstrating the robust nature of both these viscosities and oem products.

So for example a very good 5w20 conventional ExxonMobil Superflo was taken to 9100 miles and had plenty of chemical vim and vigor left!!! So I would be remiss if I said that conventional oil is no good! It is very good!! And the research shows it.

The interesting thing here is the (Mobil 0w20) synthetic does indicate a stronger additive package than the conventional. The other thing is combined with that the lower viscosity does indicate better fuel mileage. (est 1-3 mpg with most folks getting 1-2 mpg better)

This might not mean much gal to gal, but over a 10,000 mile OCI, we can be talking 8-23 gals. So at 2 dollars a gal from 16-46 dollars in fuel cost savings or 288 miles-874 miles MORE.

Two of my current vehicles actually specify "synthetic", or more technically have specifications that many synthetics meet!

Mr_Shiftright · February 2005

I still don't believe the mileage claims. It appears to always be anecdotal evidence. It's one of those "too good to be true" type of things. I've tested it time and time again using methods advised from my scientist friend (on how to approximate a scientific testing standard) on my cars and the mileage increase was really statistical irrelevant. I can't replicate the claims, so I remain skeptical. I think what I was seeing though, is a small gain from faster warm ups. Maybe I'd concede .5 mpg.

I sailed the flat earth and my ship fell off the edge:) (remember the joke about how there were originally FOUR ships with Columbus?)

ruking1 · February 2005

Pardon me for saying this, but the whole point of the UOA's is (the) ANECDOTAL (NESS)!!!!!!

We are testing in part to see what the real numbers are (for your specific car, operative parameters yada, yada,) The test was really designed to show engine operation trends, but make no mistake you can get the status of your oil!! So really the individual or YOUR test is the individual verification or vilification or anecdotal (ness) of the advertising metric!!! So conversely why would you tend to believe the qwiky lube's mantras of 3000 miles??? On testing? They do not offer testing? Marketing? etc, etc,?

..."I sailed the flat earth and my ship fell off the edge:) (remember the joke about how there were originally FOUR ships with Columbus?) "...

The one that almost never fails to give me a chuckle is the Mel Brooks schticked, where he plays Moses bringing down the three tablets of stone with the (15 commandments, ie 5 per stone) to the people.

He starts off saying: I bring to you the FIF commandments, (drops one tablet and corrects himself), I bring to you the 10 commandments!

So the good news is there are only 10, the bad news is we are inadvertently violating 5 unknown ones!!!

wtd44 · February 2005

You seem to really be hung up on the idea that all people who change their oil at 3000 mile intervals are the direct victims of quick lubrication enterprises. You leave me no choice but to shatter your belief system, but I'm sure you will be the better informed for it.

Some/many of us who change our oil at 3000 mile intervals began doing so prior to the marketing novelty of quick lubrication merchants surfaced in America. I'll let this soak in for a while, and see if it takes, or if I'll be forced to expand the topic.

ruking1 · February 2005

..."To me there is NOTHING wrong with mineral oil. I have also run 250,000 miles on a vehicle using nothing but mineral oil (just before Mobil One came to market). The changing schedule was frenetic (1500/3000 miles). And these were the days before UOA's were available.

In days past, sometimes 3000 miles was PUSHING IT!"...

I said the above in a prior post.

..."So for example a very good 5w20 conventional ExxonMobil Superflo was taken to 9100 miles and had plenty of chemical vim and vigor left!!! So I would be remiss if I said that conventional oil is no good! It is very good!! And the research shows it. "...

Would an anti conventional oil person say this?

..."Some/many of us who change our oil at 3000 mile intervals began doing so prior..."...

So if you are including me in your population then I would say I was "one of those"!

So am I hung up ? NO ! I have scrapped sludge from more engines that have had religious 3000 mile or less OCI's than I care to remember!

Relieved or grateful is more like it!

I think the good old days of lubrication ARE actually NOW !!!

wtd44 · February 2005

I have had most all those same experiences, and mostly in the long ago past, at least where sludge is concerned.

In a few hours, I will crawl under my daughter's 2004 Jeep Grand Cherokee and perform the "mandatory" 3000 mile oil and filter change, just as it states in the owners manual. And yes, these are the grand old days of engine lubrication compared to the goo scooping days of early engine rebuilds. I haven't split any engine cases in a very long time...

ruking1 · February 2005

Try as I may, after almost 1.5M million miles as a driver, I have almost forgotten when oil changing was fun!:(

I have to admit the thing that comes the closest (woo hoo) is the VW Jetta TDI with oem recommendations of 10,000 OCI's.

The real kicker is the OEM has placed the oil filter cartridge and designed the dipstick TOPSIDE; in such a way where a suction evacuator can be used to swap out oil and filter cartridge and not go under the vehicle!!!

No jacking up or down. From oil removal to replacing the oil filler cap , you can be good to go in under 15 mins!!!

While any number of CI-4 CF-4 and Euro rated so called "conventional synthetic" oils (hydrocracked PAO III) will do well, (i.e.,Shell Rotella T and/or full synthetic) I have opted for (PAO IV) Delvac One 5w40 aka Mobil One Truck & SUV. Other UOA's have indicated this can be good to 25,000 miles. Being the belt and suspenders guy I am, 20,000 miles is almost like falling off the flat earth!

At 48,000 miles, this puppy will see break-in (or full compression) at app 60,000 miles.

shipo · February 2005

I've got a pretty nice OCI on my car as well; the recommended interval is 15,000 miles or one year! Not too shabby. Actually, due to an interesting algorithm in the OBC, the car figures out when the next oil change is due based upon stuff like number of gallons of gas used, operating temperature, idle time and other voodoo type stuff. Interestingly enough, my first 15,000 miles were done partly in Europe (at high speed I might add) and then in the NYC area in heavy traffic. The OBC had me make my first oil change at about 13,500. Now that I live in New Hampshire (and regularly drive at a nice easy 80), my OBC is recommending more like 16,500 for the OCI.

Ditto on the filter cartridge, my car has that too, all I need to do for a change is to pull out the dip-stick, screw off the cap to the filter, suck out all of the oil (almost 8 quarts), swap the filter, put the cap back on, and dump in 8 quarts of Mobil-1 0W-40. ;-)

Best Regards

Shipo

ruking1 · February 2005

Ain't it cool!!??

Another thing that folks might be interested is European cars have been on so called "extended" OCI's for a few years. To use one example; Mobil One 0w40, 5w40 etc sells for the outrageous everyday USA price of 4/5 dollars per qt. European versions of the same stuff goes for 10-15 dollars per qt!!

(32oz) (liter really(33.8 oz) but for comparison purposes)

shipo · February 2005

Yeah, I noticed Mobil-1 for 10 Euros in a couple of places and I was stunned. No wonder they like the extended OCI. ;-)

Best Regards

Shipo

Mr_Shiftright · February 2005

I think I like shorter oil changes mostly because it gets me under and around the engine more often. I guess if I had a brand new 2003 or 2004 car I'd be more relaxed about it.

ruking1 · February 2005

Multi tasking is a good thing! As you allude, doing longer OCI's does not relieve one of doing the normal interval checks.

Formerly, I would not have thought I would see the day when a big vender such as Mobil go to an EP type of at need or on demand type of oil product. They have just recently announced this new type system (products are stratified) and the new products are hitting the retail markets.

Only time will tell which elixers will tough it out and emerge as the "go to" oil. I was bummed to see that Mobil One 0w20 is discontinued in favor of the new Mobil One 5w20. The verdict is still out whether 0w20 or 5w20 is better for mpg. (among other improved parameters)

shipo · February 2005

In theory at least, there should be no difference in mileage between the two except for a few moments after a cold start while the oil is warming up. I would be surprised to find that the difference was even measurable.

Best Regards,

Shipo

ruking1 · February 2005

My guess is what you said will probably be the case! I was also looking at it from the glasses of the fact that 5w20 has received severe skeptism. So a ZER Ow20 would probably be even worse. Again I am guessing, but I think one of the reasons why it may have been dropped is because of this which also would reflect in market share( or lack there of) Since 5w20 is the Ford and Honda specification this might represent the market is now growing and or accepting this product in the 5w20 market and since there is probably scant difference; makes sense to save on costs.

wtd44 · February 2005

I am considering going to 5W-30 with intent, after my Mountaineer gets past the warranty period at 30K. On the other hand, if I see evidence contrary to such a change, I may stick with it. I just can't help but think that 5W-30 would serve the longevity of the car better. I presume 5W-20 is prescribed with the undercurrent reason being CAFE.

ruking1 · February 2005

I take it your Mountaineer requires a 5w20. If and when you do switch to 5w30, if you'd care to report mileage, i.e., higher, lower, same, etc. , I for one would be interested.

wtd44 · February 2005

I'm not diligent enough on mileage tracking to give you data that would be thorough enough to be meaningful. My concern is engine longevity, really.

ruking1 · February 2005

In the process of researching the Honda Civic as it relates to the 5w20, if I had any misgivings about this viscosity, it was indeed put to rest. Honda's as you know are "little winders (whiners)".:) Be that as it may, it is a 4/6 cylinder probably subject/ed to more stress and loading that you would give to the Mountaineer. The nexus is of course to the FORD and HONDA specifications of which the 5w20 oil complies.

Indeed, if you stay with conventional oil, the 5w20's; Motorcraft, Honda oem and ExxonMobil Superflo, all have higher concentrations of moly than other vendors. This is not to say that other vendors products will not work, however it would seem these engines are more "slap happy" with higher moly dosed products. (as each oem recommends: Ford, Honda.) My oem Honda owners manual goes so far to say the oem fill needs to be in there the "full" term (10,000 miles, normal) to take advantage of the unique properties of the oem blend.

Now I will be the first to admit that it does not SPECIFICALLY say the ingredient is moly but once the oem fill is drained, practically speaking the oem has little to NO control over what brew the owner may use next.

So to keep into nexus with our thread subject, synthetic oils like Mobil One 0w20, 5w20 use a far different (approach) additive package where moly is in far less concentration.

marsha7 · February 2005

Who makes Motorcraft and Honda oil, since neither one of them is an oil co...I was using Motorcraft 5W20 synthetic in my 2004 Crown Vic, but I do not see why I can't change over to Castrol 5W30 synthetic, since that is what I use in my 2004 Ram Hemi...all good oils, and the viscosity between 20 and 30 would not cause any problems in my 4.6L Ford engine, I'm sure...

micweb · February 2005

...is that most old 5W-30 oils (not Mobil 1) would relatively quickly shear down to 20 viscosity equivalent at operating temperature (have the same thickness as a single grade 20 weight oil), whereas the 5W-20 oil spec seems to pretty much require a high component of synthetic and be more shear stable than the conventional based 5W-30 oils. Hence for all practical purposes, over most of their crankcase life, so-called 5W-20 and 5W-30 oils were both operating in a lot closer viscosity range than their labels would indicate.

OR 5W-20 oil, per se, would have been a disaster (might have been a disaster?) if Ford and Honda hadn't demanded special engineering way beyond the old SF oil spec.

Along the same logic, 5W-30 Mobil 1 is probably a better choice for cars that call for 10W-40 conventional oil; it may not start quite as thick, but it retains its viscoscity (rumor has it, no viscoscity index improvers are required for that grade). Incidentally, Mobil 1 5W-30 used to be reported as a slightly "lighter" viscosity than other 5W-30 oils, closer to a 20, but since the advent of true 20 oils, has been "thickened" a little.

On a similar "what's the real viscoscity" note, I was going to run Rotella 5-40 in my 2.0 VW, until I studied the specs on Rotella vs. VW spec'd 5-40. The VW spec is for 5-40, but at the relatively "thin" end of the 40 spectrum, actually closer to a 30 weight - which is probably why I get the same mileage with 5-40 as I did before with Mobil 1 5-30. The diesel 5-40's really are at the thicker end of the spec.

I remember reports on "high mileage" oil formulations freely admitting that they were "thicker" than other 5-30 oils....

I still don't trust oils or filters beyond 5,000 miles. I suppose if I ran a whole fleet of high mileage vehicles the net savings would outweigh an occasional incidence of unexpected wear or bearing scuffing, etc., but I don't feel like being a guinea pig for an entire industry that claims it wants to save natural resources (oil), and admirable goal, but can't build relatively defect free cars.

ruking1 · February 2005

I can understand that you do not trust oils or oil filters beyond 5,000 miles, as probably one of the hosts would agree. But really what is that trust or lack thereof based? If you said your own or similar UOA's, I would agree with you that would be based on actual and/or projected similar operation information. In that case, given today's superb conventional and synthetic engine oils, it would appear that you fall in the MOST "severe" category. Youe operation of your engine also would be wildly deviant! There are posted UOA's(other web sites) where even a conventional oil went 9,100 miles (Honda Civic, ExxonMobil 5w20 Superflo) and had plenty of chemical life left in the oil!!! (starting TBN of 7 vs 12 for Mobil One) It almost goes without saying this sets the bar very high or almost 2x higher.

As for the Mobil One 5w40 aka Delvac One 5w40 (synthetic or PAO IV) I use it in a VW Jetta TDI. It is also backwards compatible with the SL/SJ (gasser) standards (among) others). However as the 5w40 viscosity indicates, you would have or have had to decide if you want to use the 5w40 viscosity. It is a superb synthetic oil capable of going 20,000-25,000 miles between OCI's in a TDI application no less! It will probably need to be said that the TDI IS harder on engine oil than a gasser. As for me, I am saving natural resources (oil) and decreasing the cost per mile lubricated.

njpassat1 · February 2005

I just returned from the dealer for what should have been a simple procedure. Based on information found in these forums, I had tracked down Castrol Syntec 5w-40 for my '03 Passat 1.8 turbo. I made sure they were going to use the larger filter and was assured that was the case. Pointed out that I had 5 quarts of oil but that even with the larger filter it would not hold the entire 5 qts and could they please be sure not to overfill. (This is only the 3rd change since I have only 12k on the car and at both previous changes they had managed to overfill by at least a half quart each time. I know the next comment - why do I go back to this dealer??)

When they finished with the car I looked in the back seat - there's the Castrol. So much for reading the work order. They said it would be taken care of immediately - I also inquired and was told they would start over with a new filter. End of story is that I am absolutely certain they did not remove the filter and used only 4 quarts & about 2 drops of the Castrol. So now I have at least a half a quart of dino Quaker State 5w-30 ( their standard) mixed in with the synthetic oil. Does anyone know what effect this might have?? I'll change it myself to get it right and obviously won't be going back for any more oil change adventures. I just don't want to risk problems with the mix.

Let me hear from the guys who really know this stuff -

beernut · February 2005

Obviously, the answer to the overfill problem is to only give them four quarts in the first place. Put the "about 2 drops" in when you get home.

Asking the dealer to think is a mistake. No offense to dealers, everyone falls into the trap of "routine". Asking them to use your own oil which can only be found in your back seat - and THEN don't use all of it - well, that's just too non-routine.

wtd44 · February 2005

The answer to your dilemma is to do your own oil and filter changes yourself. I too have had a number of these horror show oil change fiascoes at the hands of dealerships. Mine came about when collecting on free oil and filter change offers. They were worth less than what I paid for them!

micweb · February 2005

Whatever they used in your Passat 1.8 Turbo, it SHOULDN'T have been Quaker State 5-30 - if you suspect it was, I would report it to VW Customer Care. VW has sent notices to their customers that warranties are VOID if the VW spec oil (5-40 or 0-40) is not used, so thus the only time 5-30 is appropriate is in a non-turbo application. Hopefully the dealer used their "house" 5-40 oil, not the conventional 5-30 oil.

In terms of sludging based on a portion of the crankcase being conventional oil, I would go ahead and redo the oil change. VW/Audi has one engine that is such an oil cooker that they give a quart of full synthetic for top-offs in the glove box - it isn't a matter of lack of ability to lubricate, so much as microscopic sludging of those portions of the conventional portion of the oil - the synthetic won't cook until really high temperatures, but conventional portion, mixed in there, will.

njpassat1 · February 2005

Thanks micweb - that is the information I was looking for - thoughts on the mixing of the conventional vs. synthetic oils. I have been amazed by the comments from the service dept. at VW each time I inquire about basic oil changes. They have significantly overfilled on two occasions and pointed to the big drum of Quaker 5-30 that "they use on all cars without a problem." I will be doing a filter/oil change myself this weekend to have some piece of mind.

micweb · February 2005

...on the approved VW oil list. I would ask if they used 5-30 synthetic Quaker State or the regular oil (and I think we both know what the answer will be).

Synthetic motor oil

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